The present invention relates generally to the repair of railway trucks and, more particularly, to a replacement friction shoe having a tapered, resilient elastomeric pad on the sloped surface thereof.
Friction shoe assemblies are incorporated in a railway truck in order to reduce instabilities in a railway vehicle.
Railroad trucks are well known and comprise, in part, a pair of spaced side frames connected by a transversely positioned bolster having its ends resiliently supported in the side frames respectively. The bolster, in turn, supports a body of the railroad vehicle which is cushioned by the resilient bolster side frame connection. A friction shoe is placed between each side frame column and the adjacent truck bolster end. Accordingly, each bolster end includes two friction shoe pockets, each comprising at least one sloped surface against which a corresponding sloped surface of the friction shoe abuts. The friction shoe also includes a generally flat, generally vertical face which abuts a friction wear plate welded and/or bolted to each side frame column.
Further, the damping effect of the friction shoe surfaces against both the sloped surfaces of the bolster end and the side frame column friction plates tend to provide a force to damp the oscillations of the bolster relative to the side frame to lessen the dynamic motions of the freight car.
A problem which occurs in this arrangement is that the sloped surfaces of the friction shoes tend to wear away the metal on the corresponding sloped surfaces of the bolster end. Excessive wear in the sloped surfaces of the bolster end requires that the bolster end be restored with weld material and eventually requires the replacement of the bolster, as repeated repair of such surfaces is expensive and impractical.
It has been discovered that providing the sloped surfaces of the friction shoe with elastomeric pads, such as is shown in U.S. Pat. No. 4,825,776, greatly lessens the possibility of the friction shoe wearing away the bolster end. In these combinations, the sloped surfaces of the friction shoes are adapted for securement of the elastomeric pads and said friction shoe/elastomeric pad combinations are commercially available. However, in order to incorporate a friction shoe with such prior art elastomeric pads into a service worn bolster end, the bolster end still has to be restored with weld material.